This page at Apple Support has details about how to change both the short and long username and the Home Folder name.
Here's an extract, lifted verbatim from the link above, to change the Home Folder name:
- Log out of the account you're renaming, then log in to an administrator account.
The administrator account needs to be a different account than the one you're renaming. If necessary, create another administrator account, then remove it when you're done.
- Go to the Users folder on the startup drive. The Users folder contains the home folder of the account you're renaming. Rename that account's home folder and make note of both the old name and new name. When renaming the folder, you're prompted to enter the administrator name and password that you used to log in.
- Choose Apple menu > System Preferences, then click Users & Groups.
- Click the lock icon, then enter the administrator name and password that you used to log in.
- From the list of users, Control-click or right-click the user that you want to rename. Choose Advanced Options from the shortcut menu.
- Change the “Account name” field to match the new name that you gave the home folder in the Users folder.
When modifying the account name (short name) or home folder name, it should not contain any spaces. If the current account name already contains a space, you won't be able to edit this field until the space has been removed. Click immediately after the space, or use the left arrow key to move the text insertion point immediately after the space, then press the Delete key to remove the space.
Change the “Home directory” field to match the new name that you gave the home folder in the Users folder.
Click OK, then quit System Preferences.
Restart your Mac.
Log in to the renamed account, then verify that your old files and folders are visible and the account is working as expected.